(1) Field of the Invention
The present invention relates to a broadcast apparatus, a reception apparatus, and a data transmission/reception method, and especially relates to techniques of multiplex, transmission, and reception of data to be simultaneously displayed.
(2) Prior Art
In recent digital broadcasting, additional data such as character information is multiplexed with program data such as video and audio and broadcast.
In general, the same or update additional data is repeatedly multiplexed with program data and broadcast, in a predetermined cycle such as five seconds.
After a viewer's start operation, a reception apparatus keeps the viewer waiting while the reception apparatus waits for necessary additional data for one or two cycles, processes it, and displays it.
Also, in a virtual interactive system in which a viewer repeatedly select items from displayed menus to search for necessary information, they have to wait in every selection operation.
A reception apparatus that provides desired information to a viewer shortly after the viewer's selection operation is disclosed in Japanese Laid-Open Patent Application No. H10-126753.
This reception apparatus receives navigation information which associates a plurality of pieces of image information with each other, and accumulates a piece of image information to be displayed next in a memory in advance. Accordingly, the reception apparatus intends to reduce a waiting time from the viewer's selection operation to the display of the desired image.
Here, if additional data to be multiplexed with program data is different for each program like characters or detailed information about a program, which are to be displayed simultaneously with an image of the program, additional data changes when one program changes to another. Therefore, a viewer has to wait until the reception apparatus starts to display additional data whenever one program changes to another.
Suppose there is a waiting time of seven seconds. The waiting time of seven seconds is not so problematic for a relatively long program of thirty minutes or one hour. However, the shorter a broadcast time period of a program becomes, the greater the influence with the waiting time becomes. Especially, a broadcast time period of a commercial (CM) is generally no longer than thirty seconds. In addition, a CM program has to meet a lot of requirements from its sponsor. Therefore, it is problematic if characters are not displayed even for a few seconds.
Note here that conventional reception apparatuses are not designed to handle such a problem caused when one program changes to another.